This invention relates to a lubricant additive acting as a friction modifier, and, more particularly, to a process for producing an additive which imparts enhanced fuel economy when employed in a lubricating oil composition.
The addition of oligomeric waxes or oils of polytetrafluoroethylene (PTFE) to lubricating oils is designed to reduce wear and friction on mechanized components of internal combustion engines. Less frequent replacement of worn or damaged engine components and greater gasoline efficiency are direct consequences. PTFE oils or waxes are not, however, soluble in any known lubricating oil.
Thus, it is an object of the present invention to provide a lubricating oil composition and manufacturing process for it which has enhanced fuel economy. The lubricating oil composition consists of a major portion of a lubrication oil and a minor amount of a reaction product described herein. It is prepared by the process which comprises reacting a perfluoroaliphatic alcohol with an alkenyl succinic acid anhydride to form an alkenyl succinic mono and/or diester in the presence of an acid catalyst. This invention is significant in light of the need to reduce the fuel consumed by motor vehicles in order to protect our environment and conserve our natural resources.
U.S. Pat. No. 3,933,656 discloses a method of friction reduction between metal surfaces using a dispersion of polytetrafluoroethylene in lubricating oil.
U.S. Pat. No. 4,224,173 discloses a method of using polytetrafluoroethylene dispersions in lubricating oils to reduce friction and enhance fuel economy in internal combustion engines.
U.S. Pat. No. 4,284,518 discloses a method of using a colloidal dispersion of polytetrafluoroethylene as a wear resistant additive and fuel economizer during physical operation.
U.S. Pat. Application Ser. No. 07/434,611 discloses a polymeric lubricating oil additive containing pendant perfluoroaliphatic urethane units that behaves as a VI Improver and a fuel economy enhancer when added to lubricating oil compositions. The polymeric substrate may be a copolymer of 15-85 mole% ethylene and propylene or a terpolymer of 15-85 mole% ethylene, propylene, and 2-8- mole% of a non-conjugated diene or triene (C.sub.3 -C.sub.1O) alpha olefin. The copolymer or terpolymer substrate has a molecular weight range of about 5,000 to about 500,000.
The disclosures in the foregoing patents and application which relate to VI improvers and fuel economizers for lubricating oils, namely U.S. Patents 3,933,656, 4,224,173 and 4,284,518; and U.S. Pat. Application Ser. No. 07/434,611 are incorporated herein by reference.